A private military company (PMC) is a private company providing armed combat and/or security services. They are one type of private security companies. PMCs refer to their staff as "security contractors" or "private military contractors". Private military companies refer to their business generally as the "private military industry" or "The Circuit". The United Nations, in a convention so far ratified by 35 states, considers PMCs to be mercenaries and prohibits them; the United Kingdom, Russia, China, and the United States are not signatories to the convention, and the United States has rejected the UN's classification of PMCs as mercenaries.
The services and expertise offered by PMCs are typically similar to those of governmental security, military or police forces, most often on a smaller scale. While PMCs often provide services to train or supplement official armed forces in service of governments, they can also be employed by private companies to provide bodyguards for key staff or protection of company premises, especially in hostile territories. However, contractors who use offensive force in a war zone could be considered unlawful combatants, in reference to a concept outlined in the Geneva Conventions and explicitly specified by the 2006 American Military Commissions Act.
The services of private contractors are used around the world. P. W. Singer author of Corporate Warriors: The Rise of the Privatized Military Industry says "In geographic terms, it operates in over 50 different countries. It’s operated in every single continent but Antarctica." Singer states that in the 1990s there used to be 50 military personnel for every 1 contractor, now the ratio is 10 to 1. He also points out that these contractors have a number of duties depending on who they are hired by. In developing countries that have natural resources, such as oil refineries in Iraq, they are hired to guard the area. They are also hired to guard companies that contract services and reconstruction efforts such as General Electric. Apart from securing companies, they also secure officials and government affiliates. Private military companies carry out many different missions and jobs. Some examples are supplying bodyguards to the Afghan president Hamid Karzai and piloting reconnaissance airplanes and helicopters as a part of Plan Colombia. They are also licensed by the United States Department of State, they are contracting with national governments, training soldiers and reorganizing militaries in Nigeria, Bulgaria, Taiwan, and Equatorial Guinea. According to a study from 2003 the PMC industry was worth over $100 billion a year at that time.